Onset of individual growth difference and its hereditary factors from broodstocks in larviculture of leopard coral grouper Plectropomus leopardus

Abstract

We conducted a rearing experiment of leopard coral grouper (LCG) Plectropomus leopardus larvae, and determined the growth history of larvae in order to clarify when the growth difference occurs. We also examined whether hereditary factors from broodstocks affect the growth difference of larvae. The otolith microstructure of LCG larvae was investigated to examine the individual growth history and to predict the age and body size at onset of individual growth difference. Since the total length (TL) of fish can be back-calculated from otolith radius (OR), we backc-alculated TLs of 50 fish at 50 days post hatching (dph) divided into three size groups (small, intermediate, large). Growth difference was recognized from 24 dph coinciding with the conversion of feeding regime, and the difference became larger thereafter. Growth difference was assumed to be promoted by completion of metamorphosis of LCG larvae. Furthermore, chi-square randomization tests (Monte Carlo Technique) of genotype variation for the three size groups of 50 dph suggested that the hereditary influence from the broodstocks on the growth difference was not significant.